const directive = {
  //el: HTMLElement,绑定的父级DOM//     binding: DirectiveBinding//指令传来的参数对象
  mounted(el, binding) {
    binding.value ? binding.value : (binding.value = {});
    addWaterMarker(
      binding.value.text,
      el,
      binding.value.font,
      binding.value.textColor
    );
  },
};

function addWaterMarker(str, parentNode, font, textColor) {
  // 水印文字，父元素，字体，文字颜色
  var can = document.createElement("canvas");
  parentNode.appendChild(can);
  can.width = 200;
  can.height = 150;
  can.style.display = "none";
  var cans = can.getContext("2d");
  cans.rotate((-20 * Math.PI) / 180);
  cans.font = font || "16px Microsoft JhengHei";
  cans.fillStyle = textColor || "rgba(180, 180, 180, 0.3)";
  cans.textAlign = "left";
  cans.textBaseline = "middle";
  cans.fillText(str || "vue-admin-box", can.width / 10, can.height / 2);
  parentNode.style.backgroundImage = "url(" + can.toDataURL("image/png") + ")";
}

export default directive;
